The purpose of this project is to study infant deaths among Native American Indians (specifically the Aberdeen area of South Dakota). This will be an in-depth study to learn why the SIDS rates among Northern Plains Indians are 4-5 times the national average. This contract will be a systematic analysis of the brains of all infants autopsied in the Infant Mortality Study of the Aberdeen Area. The neuropathologic analysis is necessary to (1) make an accurate classification of cause of death, (2) obtain baseline information on the types and frequency of brain lesions in the population, (3) determine if there is an association of specific brain lesions with risk factors such as prenatal exposure to alcohol or cigarette smoking, and (4) investigate brain lesions that may be important neural mechanisms of SIDS.